body {
    display: flex;
    flex-direction: column;
    height: 100svh;
    margin: 0;
}

main {
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    padding: 10px;
    height: 100%;
}

.images-difference {
    position: relative;
    width: 400px;
    height: 400px;
    cursor: ew-resize;
}

.images-difference > .curtain {
    display: none;
    position: absolute;
    top: 0;
    height: 100%;
    width: 3px;
    background-color: red;
}

.images-difference > .images-container {
    width: 100%;
    height: 100%;
}

.images-difference > .images-container > .difference-image {
    position: absolute;
    width: 100%;
    height: 100%;
    background-size: cover;
}

.images-difference > .images-container > .difference-image.first {
    background-image: url("../img/img1.jpg");
}

.images-difference > .images-container > .difference-image.second {
    background-image: url("../img/img2.jpg");
}